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9/4/2013
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Echinodermata Gr: spine skin
1) pentamerous radial symmetry (adults)
2) spines
3) endoskeleton
4) water vascular system (WVS)
6500 spp all marine except for few estuarine, none freshwater
ossicles
calcareous plates
mesodermally-derived
5) tube feet (podia)
up to 95% CaCO3, up to 15% MgCO3, salts,
trace metals, small amount of organic materials
*larvae bilateral symmetrical
Echinodermata Classes:
1) Asteroidea
2) Ophiuroidea
3) Echinoidea
5) Crinoidea
4) Holothuroidea
1700 spp
2100 spp
1000 spp
(Gr: snake-tail-like)
stalked – 100 spp
nonstalked, motile comatulid
(feather stars)- 600 spp
(Gr: lily-like)
(Gr: characterized by star-like)
(Gr: hedgehog-form)
1200 spp
(Gr: sea cucumber-like)
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Asteroidea sea stars/starfish
spines fixed
pedicellariae
ambulacral groove open
tube feet with suckers on oral side
arms not sharply marked off
from central star shaped disc
anus/madreporite aboral
Figure 22.01
Pincushion star, Culcita navaeguineae,
preys on coral polyps,
small organisms & detritus
Choriaster granulatus scavenges
dead animals on shallow Pacific reefs
On the Great Barrier Reef, Tosia queenslandensis
browses encrusting organisms
Crown-of-thorns star, Acanthaster planci
forages on corals
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Spines Tube Feet
Figure 22.03a
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Figure 22.03b
Figure 22.03c
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Figure 22.04
Pedicellaria
Pedicellariae
Figure 22.04a
Pedicellaria
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Figure 22.06
this lower stomach
everted out during
extracellular digestion
pyloric stomach
Figure 22.05
Orthasterias koehleri eating a clam Sun star, Pycnopodia helianthoides